zipcar/uber: A service that delivers a car you drive to where you are when you want it. Maybe you call up an hour before or via an app. And/or the opposite: you have driven somewhere can don't want the car anymore - eg drinking.
Taxis are great for some situations but not others. 1. Say you are working late (the train service has closed) and know you'll leave in the next 3 hours. Order a car to be delivered to your parking lot and just get into it whenever your finish work. 2. How about the dreaded: other people offering you a ride since you don't have a car. You would be very happy to take a taxi but they insist. No problem; order up a car and its waiting for you when you leave the meeting and nobody will have to take "help you out".